Microsoft announced Monday that Steven Sinofsky, president of Microsoft's Windows and Windows Live division, is leaving the company.

Why?

Microsoft doesn't say in its statement announcing the change.

C'mon. What are people saying?

There's a range - from wanting to take over as CEO from Steve Ballmer, to lacking the vision to encompass all of Microsoft and not just his fiefdom, to being difficult to work with.

Did he screw up Windows 8?

He delivered it on time with the innovative Microsoft Surface tablet/notebooks to boot, and so far the jury is out on whether they will be successful. But there's no obvious problem with the products to indicate his head had to roll.

What does Sinofsky say?

Here's an explanation from a letter he wrote to Microsoft employees that was obtained by Paul Thurrott's Super Site for Windows. "Some might notice a bit of chatter speculating about this decision or timing. I can assure you that none could be true as this was a personal and private choice that in no way reflects any speculation or theories one might read about me, opportunity, the company or its leadership."

Who replaces him?

Two current executives are taking over his role and report directly to CEO Steve Ballmer. They are Julie Larson-Green and Tami Reller.

What are Larson-Green's credentials?

Larson-Green is vice president of program management for Windows and has worked at Microsoft for 19 years. She has worked on improving user experience for early versions of Internet Explorer and the refresh of Microsoft Office. She played a major role in development of both Windows 7 and Windows 8, heading up program management, user interface design and research and development of international releases of both.

What about Reller?

Reller is chief financial officer and chief marketing officer of Windows and Windows Live. She has worked for Microsoft since 2001 when it acquired Great Plains Software where she had worked since 1984 and served as CFO.

What will they be in charge of now that Windows 8 and Microsoft Surface have shipped?

Larson-Green will oversee all Windows software development as well as any new hardware. Reller will hold onto her current jobs and add responsibility for business and marketing strategy for Windows devices, including Surface and partner devices.

Will someone be appointed president of Windows and Windows live, Sinofsky's old title?

That's unclear. While Larson-Green is being promoted, Microsoft doesn't say what title she's being promoted to.

What's Sinofsky going to do?

Microsoft doesn't address this.

(Tim Greene covers Microsoft for Network World and writes the Mostly Microsoft blog. Reach him at tgreene@nww.com and follow him on Twitter https://twitter.com/#!/Tim_Greene.)

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